/*
 * Copyright (C) 2008 Apple Inc. All rights reserved.
 * Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies)
 * Copyright (C) 2013 Xidorn Quan (quanxunzhen@gmail.com)
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1.  Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 * 2.  Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "flutter/sky/engine/platform/geometry/FloatQuad.h"

#include <algorithm>
#include <limits>

namespace blink {

static inline float min4(float a, float b, float c, float d) {
  return std::min(std::min(a, b), std::min(c, d));
}

static inline float max4(float a, float b, float c, float d) {
  return std::max(std::max(a, b), std::max(c, d));
}

inline float dot(const FloatSize& a, const FloatSize& b) {
  return a.width() * b.width() + a.height() * b.height();
}

inline float determinant(const FloatSize& a, const FloatSize& b) {
  return a.width() * b.height() - a.height() * b.width();
}

inline bool isPointInTriangle(const FloatPoint& p,
                              const FloatPoint& t1,
                              const FloatPoint& t2,
                              const FloatPoint& t3) {
  // Compute vectors
  FloatSize v0 = t3 - t1;
  FloatSize v1 = t2 - t1;
  FloatSize v2 = p - t1;

  // Compute dot products
  float dot00 = dot(v0, v0);
  float dot01 = dot(v0, v1);
  float dot02 = dot(v0, v2);
  float dot11 = dot(v1, v1);
  float dot12 = dot(v1, v2);

  // Compute barycentric coordinates
  float invDenom = 1.0f / (dot00 * dot11 - dot01 * dot01);
  float u = (dot11 * dot02 - dot01 * dot12) * invDenom;
  float v = (dot00 * dot12 - dot01 * dot02) * invDenom;

  // Check if point is in triangle
  return (u >= 0) && (v >= 0) && (u + v <= 1);
}

FloatRect FloatQuad::boundingBox() const {
  float left = min4(m_p1.x(), m_p2.x(), m_p3.x(), m_p4.x());
  float top = min4(m_p1.y(), m_p2.y(), m_p3.y(), m_p4.y());

  float right = max4(m_p1.x(), m_p2.x(), m_p3.x(), m_p4.x());
  float bottom = max4(m_p1.y(), m_p2.y(), m_p3.y(), m_p4.y());

  return FloatRect(left, top, right - left, bottom - top);
}

static inline bool withinEpsilon(float a, float b) {
  return fabs(a - b) < std::numeric_limits<float>::epsilon();
}

bool FloatQuad::isRectilinear() const {
  return (withinEpsilon(m_p1.x(), m_p2.x()) &&
          withinEpsilon(m_p2.y(), m_p3.y()) &&
          withinEpsilon(m_p3.x(), m_p4.x()) &&
          withinEpsilon(m_p4.y(), m_p1.y())) ||
         (withinEpsilon(m_p1.y(), m_p2.y()) &&
          withinEpsilon(m_p2.x(), m_p3.x()) &&
          withinEpsilon(m_p3.y(), m_p4.y()) &&
          withinEpsilon(m_p4.x(), m_p1.x()));
}

bool FloatQuad::containsPoint(const FloatPoint& p) const {
  return isPointInTriangle(p, m_p1, m_p2, m_p3) ||
         isPointInTriangle(p, m_p1, m_p3, m_p4);
}

// Note that we only handle convex quads here.
bool FloatQuad::containsQuad(const FloatQuad& other) const {
  return containsPoint(other.p1()) && containsPoint(other.p2()) &&
         containsPoint(other.p3()) && containsPoint(other.p4());
}

static inline FloatPoint rightMostCornerToVector(const FloatRect& rect,
                                                 const FloatSize& vector) {
  // Return the corner of the rectangle that if it is to the left of the vector
  // would mean all of the rectangle is to the left of the vector.
  // The vector here represents the side between two points in a clockwise
  // convex polygon.
  //
  //  Q  XXX
  // QQQ XXX   If the lower left corner of X is left of the vector that goes
  // from the top corner of Q to
  //  QQQ      the right corner of Q, then all of X is left of the vector, and
  //  intersection impossible.
  //   Q
  //
  FloatPoint point;
  if (vector.width() >= 0)
    point.setY(rect.maxY());
  else
    point.setY(rect.y());
  if (vector.height() >= 0)
    point.setX(rect.x());
  else
    point.setX(rect.maxX());
  return point;
}

bool FloatQuad::intersectsRect(const FloatRect& rect) const {
  // For each side of the quad clockwise we check if the rectangle is to the
  // left of it since only content on the right can onlap with the quad. This
  // only works if the quad is convex.
  FloatSize v1, v2, v3, v4;

  // Ensure we use clockwise vectors.
  if (!isCounterclockwise()) {
    v1 = m_p2 - m_p1;
    v2 = m_p3 - m_p2;
    v3 = m_p4 - m_p3;
    v4 = m_p1 - m_p4;
  } else {
    v1 = m_p4 - m_p1;
    v2 = m_p1 - m_p2;
    v3 = m_p2 - m_p3;
    v4 = m_p3 - m_p4;
  }

  FloatPoint p = rightMostCornerToVector(rect, v1);
  if (determinant(v1, p - m_p1) < 0)
    return false;

  p = rightMostCornerToVector(rect, v2);
  if (determinant(v2, p - m_p2) < 0)
    return false;

  p = rightMostCornerToVector(rect, v3);
  if (determinant(v3, p - m_p3) < 0)
    return false;

  p = rightMostCornerToVector(rect, v4);
  if (determinant(v4, p - m_p4) < 0)
    return false;

  // If not all of the rectangle is outside one of the quad's four sides, then
  // that means at least a part of the rectangle is overlapping the quad.
  return true;
}

// Tests whether the line is contained by or intersected with the circle.
static inline bool lineIntersectsCircle(const FloatPoint& center,
                                        float radius,
                                        const FloatPoint& p0,
                                        const FloatPoint& p1) {
  float x0 = p0.x() - center.x(), y0 = p0.y() - center.y();
  float x1 = p1.x() - center.x(), y1 = p1.y() - center.y();
  float radius2 = radius * radius;
  if ((x0 * x0 + y0 * y0) <= radius2 || (x1 * x1 + y1 * y1) <= radius2)
    return true;
  if (p0 == p1)
    return false;

  float a = y0 - y1;
  float b = x1 - x0;
  float c = x0 * y1 - x1 * y0;
  float distance2 = c * c / (a * a + b * b);
  // If distance between the center point and the line > the radius,
  // the line doesn't cross (or is contained by) the ellipse.
  if (distance2 > radius2)
    return false;

  // The nearest point on the line is between p0 and p1?
  float x = -a * c / (a * a + b * b);
  float y = -b * c / (a * a + b * b);
  return (((x0 <= x && x <= x1) || (x0 >= x && x >= x1)) &&
          ((y0 <= y && y <= y1) || (y1 <= y && y <= y0)));
}

bool FloatQuad::intersectsCircle(const FloatPoint& center, float radius) const {
  return containsPoint(
             center)  // The circle may be totally contained by the quad.
         || lineIntersectsCircle(center, radius, m_p1, m_p2) ||
         lineIntersectsCircle(center, radius, m_p2, m_p3) ||
         lineIntersectsCircle(center, radius, m_p3, m_p4) ||
         lineIntersectsCircle(center, radius, m_p4, m_p1);
}

bool FloatQuad::intersectsEllipse(const FloatPoint& center,
                                  const FloatSize& radii) const {
  // Transform the ellipse to an origin-centered circle whose radius is the
  // product of major radius and minor radius. Here we apply the same
  // transformation to the quad.
  FloatQuad transformedQuad(*this);
  transformedQuad.move(-center.x(), -center.y());
  transformedQuad.scale(radii.height(), radii.width());

  FloatPoint originPoint;
  return transformedQuad.intersectsCircle(originPoint,
                                          radii.height() * radii.width());
}

bool FloatQuad::isCounterclockwise() const {
  // Return if the two first vectors are turning clockwise. If the quad is
  // convex then all following vectors will turn the same way.
  return determinant(m_p2 - m_p1, m_p3 - m_p2) < 0;
}

}  // namespace blink
